Interstellar dust isn’t especially rare – space is full of it and tonnes of the stuff reach the Earth each day, the residue of passing comets, asteroids and exploding stars.
But finding interstellar dust that reached Earth recently is unusual, and this discovery offers new insights into the nature and formation of the solar system, according to a new study published in the journal Physical Review Letters.
Lead author Dominik Koll, an experimental nuclear physicist at the Australian National University in Canberra, said scientists might be able to use these results to figure out how the solar neighbourhood was shaped.
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“We know something about distant galaxies and stars and a lot about our solar system, but the nearby surroundings of our solar system need more investigation,” he told space.com.
In the search for pristine examples of interstellar dust, scientists collected about 500 kilograms of Antarctic snow that was less than 20 years old. That came from inland Antarctica, near Germany's Kohnen Station.
In Munich, Germany, it was melted, filtered to remove solids, and the residue incinerated and light pattern analysed – revealing the presence of two rare, mildly radioactive metal isotopes: iron-60 and manganese-53.
They concluded that the most likely source of the iron-60 was a supernova, the explosion of a dying star, as other natural means of creating iron-60 produce only much smaller quantities.
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Iron-60 and manganese-53 also can be produced when cosmic rays strike interplanetary dust. However, the researchers found a greater ratio of iron-60 to manganese-53 than would be expected from this mechanism.
There was another possibility – fallout from nuclear weapons or power plants. They concluded that iron-60 and manganese-53 from these sources should be in negligible quantities.
That left just only one other possibility – the material originated in space, most likely created in a nearby supernova producing clouds of interstellar gas and dust, through which the solar system passes, with the dust reaching the Earth’s surface.
Researchers said future examination of interstellar dust in older snow and ice could shed light on origins and structure of nearby interstellar clouds and the history of their interactions with our solar system.
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